People are heterogeneous! The first year is really easy and enjoyable for me. I think the two best suggestions (for people in quant marketing or other quantitative fields) are:
1 Have a great rest before starting the program. Preparation in advance at the current stage doesn't matter much, while a relaxed body/mind helps a lot.
2 Don't do any research. Instead, focus on the coursework.
But again, as I said, people are heterogeneous. You should find the best strategy for yourself.